Array formula failing to return a blank when it should

This array formula is failing to return a blank cell when the IF / OR is true. Any help to correct it would be appreciated.

=IF(OR(K89="",K89+'GPlan'!$H$6>MAX('GPlan'!$N$18:'GPlan'!$N$301)),"",MIN(IF('GPlan'!$N$18:'GPlan'!$N$301>=(K89+'GPlan'!$H$6),'GPlan'!$N$18:'GPlan'!$N$301)))

Column K contains dates interspersed with some blank rows, Column 'GPlan' N contains dates interspersed with some blank rows and 'GPlan'!$H$6 contains a number.
So the formula looks in K89 and should return a blank when the if /or statement is true, it doesn't it returns a #Value!

I should say that if K89 contains a date , the formula works perfectly, returning the correct date or a blank , but if K89 is blank it fails and returns #Value!

Thanks for your help.

I haven't looked at the attachment but I can see a problem with your formula. When K89 contains a "formula blank" like "" then this part

K89+'GPlan'!$H$6

is still evaluated and because it's adding a text value to a number, excel returns # VALUE! error. Try using two IFs rather than OR so that if K89 = "" the K89+'GPlan'!$H$6 part is not executed, i.e.

=IF(K89="","",IF(K89+'GPlan'!$H$6>MAX('GPlan'!$N$18:$N$301),"",MIN(IF('GPlan'!$N$18:$N$301>=K89+'GPlan'!$H$6,'GPlan'!$N$18:$N$301))))

Hi Daddylonglegs

Thanks for helping out, your solution seems to be working perfectly now that I've tried it in the real workbook, Great !!

Many thanks and regards.